Fix floating point window range extents. #13606
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This commit fixes the window range calculations for floating-point order by columns. Window range calculations involve comparing the `delta` value (preceding/following) with the current row value, and capping `current_row - delta` at `numeric_limits::min()`. It turns out that for `float`/`double` values, `numeric_limits::min()` returns `FLT_MIN` which is the lowest positive finite float value. This causes the erstwhile logic to produce incorrect results when the order-by column contains negative float values. The fix involves replacing `numeric_limits::min()` with `numeric_limits::lowest()` which returns the true min float value. Reference: 1. https://en.cppreference.com/w/cpp/types/numeric_limits/min
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This is a follow-up to rapidsai#13512 (which added support for floating point order-by columns in window functions), and rapidsai#13606 (which fixed how negative values are handled for floating point order-by). This commit fixes how `NaN` and `+/- Infinity` values are handled for floating point. Prior to this commit, the calculations for range window extents depended on the behaviour of `thrust::less<float>` and `thrust::greater<float>`, as well as addition/subtraction on `+/- Infinity`. This produced some unexpected results: 1. `thrust::less`/`greater` on `NaN` does not produce strict ordering. 2. Addition/Subtraction on the numerical values of `Infinity` could produce finite values that interfere with window extent calculations. Ideally, the results should have remained infinite. This commit adds custom comparators with `NaN` awareness, to better handle columns that contain `NaN`s. It also fixes range calculations where `Infinity` is involved. Tests have been added to cover ASC/DESC order sorting on `FLOAT`, with `NaN` and `Infinity` values.
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This is a follow-up to #13512 (which added support for floating point order-by columns in window functions), and #13606 (which fixed how negative values are handled for floating point order-by). This commit fixes how `NaN` and `+/- Infinity` values are handled for floating point. Prior to this commit, the calculations for range window extents depended on the behaviour of `thrust::less<float>` and `thrust::greater<float>`, as well as addition/subtraction on `+/- Infinity`. This produced some unexpected results: 1. `thrust::less`/`greater` on `NaN` does not produce strict ordering. 2. Addition/Subtraction on the numerical values of `Infinity` could produce finite values that interfere with window extent calculations. Ideally, the results should have remained infinite. This commit adds custom comparators with `NaN` awareness, to better handle columns that contain `NaN`s. It also fixes range calculations where `Infinity` is involved. Tests have been added to cover ASC/DESC order sorting on `FLOAT`, with `NaN` and `Infinity` values. Authors: - MithunR (https://github.com/mythrocks) Approvers: - Vukasin Milovanovic (https://github.com/vuule) - Mike Wilson (https://github.com/hyperbolic2346) - https://github.com/nvdbaranec URL: #13635
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Description
This commit fixes the window range calculations for floating-point order by columns.
Window range calculations involve comparing the
deltavalue (preceding/following) with the current row value, and cappingcurrent_row - deltaatnumeric_limits::min().It turns out that for
float/doublevalues,numeric_limits::min()returnsFLT_MINwhich is the lowest positive finite float value. This causes the erstwhile logic to produce incorrect results when the order-by column contains negative float values.The fix involves replacing
numeric_limits::min()withnumeric_limits::lowest()which returns the true min float value.Reference:
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